Vulcanizable epihalohydrin polymer composition

ABSTRACT

A vulcanizable epihalohydrin-polymer elastomer comprising (1) an epihalohydrin-polymer elastomer, (2) at least one metal cyanate selected from the group consisting of cyanates of matals of Groups IA, IB, IIA, IIB and IVB of the periodic table, and (3) a functional compound selected from the group consisting of (i) compounds obtained by substituting at least two hydroxyl groups or mercapto groups for hydrogen atoms in a saturated hydrocarbon molecule, (ii) compounds obtained by substituting at least one hydroxyl group and at least one mercapto group for hydrogen atoms in a saturated hydrocarbon molecule, and (iii) compounds obtained by substituting at least one hydroxyl group and for mercapto group and one amino or imino group for hydrogen atoms in a saturated hydrocarbon molecule.

United States Patent, 1

Karatsu Aug. 28, 1973 VULCANIZABLE EPIHALOHYDRIN Primary ExaminerWilliam H. Short POLYMER COMPOSITION Assistant Examiner-Earl A. Nielsen Attorney-Leonard W. Sherman, Edwin A. Shallo' [75] Inventor: Tetsuo Karatsu, Yokohama, Japan way et al.

[73] Assignee: Nippon Zeon Co., Ltd.,Tokyo, Japan ABSTRACT A vulcanizable epihalohydrin-polymer elastomer com- Filed: 1972 prising (1) an epihalohydrin-polymer elastomer, (2) at [52] U.S. Cl. 260/2 A, 260/79 R [51] Int. Cl. C08g 23/20 [58] Field of Search 260/2 A, 79 R [56] References Cited UNITED STATES PATENTS 3,341,491 9/1967 Robinson 260/45.75 3,420,794 l/1969 May et al 260/47 3,624,029 11/1971 lnagami et a1. 260/45.9 R 10/1972 Hani et al. 260/79 least one metal cyanate selected from the group consisting of cyanates of matals of Groups 1A, 18, 11A, 11B and WE of the periodic table, and (3) a functional compound selected from the group consisting of (1) compounds obtained by substituting at least two hydroxyl groups or mercapto groups for hydrogen atoms in a saturated hydrocarbon molecule, (ii) compounds obtained by substituting at least one hydroxyl group and at least one mercapto group for hydrogen atoms in .a saturated hydrocarbon molecule, and (iii) com- 11 Claims, 4 Drawing Figures PATENTEDIIIII22B I975 SHEET 1 BF 2 EXPERIMENT 5 EXPERIMENT 4 EXPERIMENT 3 EXPERIMENT I EXPERIMENT s EXPERIMENT 2 3 40 I 50 VULCANIZATION TIME (min) Fig mu O 4 a m m 0 EEE wnomoP E5281.

8 7 T T m m M W R R N E a a 3 VULCANIZATION TIME A QV Macao 5523:.

(min)' PATENTEDAUGZB I975 3.755; 201 SHEET 2 [1F 2 LU 8 30- F/ 9- 3 EXPERIMENT 9 g EXPERIMENT l4 20 EXPERIMENT Io,II,I2 E EXPERIMENT l3 Io- LU I E l l I l 0 I0 20 30 4o VULCANIZATION TIME (min) Fig. 4

LU 8 30' EXPERIMENT I5 0:?- EXPERIMENT l8 EXPERIMENT f5 ,9 9 EXPERIMENT 'l7 2 20- my LLI I0- 8 :I: 0: I I l VULCANIZATION TIME (min) -VULCANIZABLE EPIHALOHYDRIN POLYMER COMPOSITION 'This invention relates to a vulcanizable composition, and more specifically ,to a novel vulcanizable composition comprising an epihalohydrin-polymer elastomer.

Known methods of vulcanizing epihalohydrin polymer elastomers include a method in which 2- mercaptoimidazoline .or thiourea and an oxide, organic acid salt or inorganic acid salt of a metal of Group "A, "B or N8 of the periodic table are conjointly used, a method wherein a polyamine is used, or a method in which an amine and .sulfur or a sulfur-containing compound are used together. Various problems arise, however, partly because of the characteristics of the epihalohydrin polymer elastomer itself, when the elastomer is vulcanized by such a known method. The most serious problem lies in the marked contamination and corrosion of vulcanization dies. In addition, the blend of rubber and compounding agents frequently adheres to the mixer during the mixing operation, and the vulcanization product is difficult to release from the die. There .are also the defects of insufficient thermal stability of the vulcanization product, and of the high permanent compression set of the vulcanization product. These problems are yet to be solved.

Accordingly, an object of this invention is to provide a vulcanizable epihalohydrin polymer elastomer composition which causes an extremely reduced contamination and corrosion of the die.

Another object of this invention is to provide a vulcanizable epihalohydrin polymer elastomer having superior miscibility and-no appreciable adherence to the mixer in the tacky state.

Still another objectof this invention is to provide-a vulcanizable epihalohydrin polymer elastomer capable of giving a vulcanizate which has good die releasability,

and improved thennal stability and permanent compression set.

It has been found :that the above objects can be achieved in accordance with this invention by a composition comprising (l).an epihalohydrin polymer elastomer, (2) at least one metal cyanate'selected from the groupconsisting of cyanates of metals of Groups IA, 18, [1A, [1B and IVB of the periodic table, and (3) at least one functional compound selected from the group consisting of (i) compounds obtained by substituting at least two hydroxyl groups or mercapto groups for hydrogen atoms in a saturated hydrocarbon molecule, (ii) compounds obtained-by substituting at least one bydroxyl group and at least one mercapto group for .hydrogen atoms in a saturated hydrocarbon molecule, and (iii) compounds. obtained by substituting at least one hydroxyl groupand/or mercapto groups and one amino group or imino group for hydrogen atoms in a saturated hydrocarbon molecule.

Examples of the cyanates of metals of groups lA, lB, "A, "B or lVB of the periodic table are cyanates of sodium, potassium, silver, barium, mercury, silicon and lead. Of these, the cyanates of sodium, potassium, and lead are especially preferred.

Examples of compound (i) having at least two hydroxyl or mercapto groups substituted for hydrogen atoms in a saturated hydrocarbon molecule include ethylene glycol, diethylene glycol, triethylene glycol, glycerol, pentaerythritol, sorbitol, ethane dithiol, propane dithiol, butane dithiol, hexane dithiol, and trithioglycerol. Typical examples of compound (ii) having at least one hydroxyl group and at least one mercapto group substituted for hydragen atoms in a saturated hydrocarbon molecule are thioglycerol, and dithioglycerol. Examples of compound (iii) having at least one of hydroxyl group and mercapto group and/or one amino group substituted for hydrogen atoms or imino group in a saturated hydrocarbon molecule are ethanolamine, diethanolamine, Z-mercaptoprbpylamine, and l mercapto-3- aminocyclohexane. The number of functional groups contained in compound (i), (ii), or (iii) may be at least 2, and there is no particular upperlimit to this number. Usually, however, the preferred number is from 2 to 6. Functional compounds having 2 to 6 hydroxyl groups are most preferred in the present invention.

In the present invention, the conjoint use of the metal cyanate and the functional compound as a vulcanizing agent is essential. If used individually, they cannot cause the vulcanization of epihalohydrin polymer elastomers.

The epihalohydrin polymer elastomers (1) used in the present invention are homopolymer rubbers of epihalohydrins'such asepichlorohydrin or epibromohydrin, copolymer rubbers of different epihalohydrins, and copolymer rubbers of epihalohydrins with other comonomers. Examples of the comonomers that can be used to prepare the copolymers include epoxides such as ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, butadiene monoxide, .ethyl gl-ycidyl ether, allyl .glycidyl ether, tetrahydrofuran and trioxane; isocyanates such as ethyl isocyanate, phenyl isocyanate and 2,4-tolylene diisocyanate; cyclic acid anhydrides such as maleic anhydride, succinic anhydride, and phthalic anhydride; acrylates; vinyl ketones; and olefins. 1

.The amount of the vulcanizing agent that is used in the present invention varies according to the desired rate of vulcanization and degree of vulcanization. Generally, 0.5 to 15 parts by weight, usually 3 to IO-parts by weight, of the metal cyanate, and 0.1 to '10 part by weight, usually I to 5 parts by weight, of the functional compound, both per l00parts by weight of the epihalohydrin polymer elastomer are used. v

The vulcanizable composition of this invention can be prepared with simplicity. by mixing the epihalohydrin polymer elastomer (l) with the metal cyanate (2) and the functional compound (3) as vulcanizing agents in accordance with an ordinary procedure such as roll mixing, Banbury mixing, or solution mixing. The conditions for vulcanizing this composition .are not particularly restricted. Usually, the vulcanization of the com position is carried out conveniently by heating it at to C. forseveral minutes to several'days. If desired, the vulcanization product can be heated for 1 hour to 3 days at 100 to 180C.

If desired, the composition of this invention may include additional rubber compounding agents such as metal oxides, reinforcing agents, fillers, softening agents, plasticizers, antioxidants, or stabilizers. The composition of this invention which further contains as a fourth component an oxide of a metal of Group IIB or lV-B of the periodic table, such ,as magnesia and red lead has improved properties with respect to the rate of vulcanization and the degree of vulcanization.

The epihalohydrin polymer elastomer compositions of this invention, without vulcanization, or with vulca- 2-mercaptoethylamine,

rheometer.

EXAMPLE I The ingredients shown in Table l were mixed with one another by means of a 6-inch roll cooled with water.

TABLE 1 Runs:

Ingredients 1 2 3 4 5 6 (parts by weight) Epichloroh drin polymer ru ber" 100 I I00 I00 I00 I00 Tin stearate 2 2 2 2 2 2 FEF carbon black 40 40 40 40 40 40 Sodium cyanate l0 l0 3 IO Glycerol 3 v 3 3 3 Magnesia 5 5 5 5 Referential Example; "Hydrin 100 (tradename, BF. Goodrich Co.)

In Runs Nos. 1, 3, 4 and Sin which glycerol was compounded in accordance with the present invention, there was a reduced adhesion of the tacky blend to the roll, and it was easy to prepare the rubber blend. The vulcanization characteristics of each of the resultant rubber blends were measured at 155C. using an oscillating disk rheometer (Toyo Seiki Co., Ltd.). This rheometer was adapted to measure the torque which is exerted on its double conical rotor when the rotor is vibrated with an angle of 3 at a speed of 3 revolutions per minute. The faster the rise of the curve drawn by the rheometer, the larger is the rate of vulcanization. Also, larger torques mean higher degrees of vulcanization. The results are shown in FIG. I. It is seen from this figure that the vulcanizing agent used in the present invention is suitable as a vulcanizing agent for the epichlorohydrin polymer rubber. It is also noted that by using magnesia conjointly or changing the amount of sodium cyanate, the rate of vulcanization and the degree of vulcanization can be freely changed.

When sodium cyanate was used alone or in combination with magnesia, vulcanization of the composition hardly occurred.

EXAMPLE 2 The procedure of Example I was repeated except that the amount of glycerol in Run No. 5 of Example 1 was changed to one part by weight (Run No. 7), and 2 parts by weight (Run No. 8) to prepare rubber blends. The vulcanization characteristics of the resulting rubber blends were measured by an oscillating disk rheometer at 155C. The results are given in FIG. 2.

EXAMPLE 3 The procedure of Example 1 was repeated except that instead of 3 parts of glycerol in Run No. 4 of Example l, 3 parts of each of the functional compounds shown in Table 2 were used, to prepare rubber blends. The vulcanization characteristics of the resulting rubber blends were measured at 155C. using an oscillating disk rheometer. The results are given in FIG. 3. The iofll processability of each blend at the time of mixing was good.

TABLE 2 Runs Functional compounds 9 Ethanolamine l0 Ethylene glycol Il Triethylene glycol 12 Diethylene glycol 13 Pentaerythn'tol l4 Thioglyeerol EXAMPLE 4 The processability of the compounding ingredients shown in Table 3 at the time of mixing by roll, the vulcanization characteristics of the rubber blend obtained (rheometer, 155C.), the mold releasing of the vulcanization product, the corrosive action of the vulcanization product on metal, and the physical properties of the vulcanization product were tested in accordance with JIS K-630l. The results are shown in FIGS. 3 and 4.

It is evident from FIGS. 3 and 4 that the vulcanization agents used in the invention provide a slightly slower rate of vulcanization than the conventional vulcanization agent in the Referential Example, but the properties of the vulcanization products are equal. Furthermore, the vulcanization agents of this invention provide excellent roll processability, mold releasing, and noncorrosive attack on metal. The composition of the invention therefore has great utility.

[Compounding Ingredients. pans by weight] Epichlorohydrin polymer rubber (Hydrin I00) Tin stearate FEF carbon black 2 .2' Methylenebis-(4-methyl-6- terL-butylphenol) Lead cyanate Glycerol Z-Mercaptobenzimidazole Red lead Hexamethylenediamine carbamate [Roll Processability] [Corrosive attack on metalsl IC X 24 hours C X 48 hours 150C X 96 hours TABLE 3 Continued Mold releasing Excellent Excellent Excellent Tensile strength (Kglcm I24 I I7 I26 300% modulus (Kg/cm) 79 66 77 Elongation 570 630 590 Hardness (JIS) 63-59 63-59 63-55 (Referentizrl Example) Good I28 79 590 53-59 An unvulcanized rubber blend is held between two stainless steel plates (SAE I020). and clamped with a bolt. It is then heated in an oven. and withdrawn after a lapse of a predetermined time. The surface of the plate which has been in contact with the rubber blend is wiped with dilute hydrochloric acid, and then washed with toluene. The corrosion of that surface is examined with the naked eye.

EXAMPLE 5 Rubber blends were prepared in the same way as set forth in Example I using the ingredients shown in Table 4. The resulting blends were tested as to corrosive attack on metal. The blends were then vulcanized at 155C. for 30 minutes, and the physical properties of the resulting vulcanization products were measured. The results obtained are shown in Table 4. In the permanent compression set test, the vulcanization product was heated at 150C. for 4 hours before the test.

TABLE 4 Run No. 22 I9 20 (Referential v Example) [Compounding ingredients, parts y \vei t] Epichlorohydrin polymer rubber (Hydrin I) I00 I00 I00 I00 Tin stearate 2 2 2 2 FEF carbon black 40 40 40 40 Phenyl-beta-napthylamine I I l 1 Lead cyanate 3 3 3 Sorbitol 3 3 3 2-Merc toimidazoline I 5 Red le 5 5 5 Magnesia 5 5 [Corrosive Attack on Metal] I50C X I hours 0 0 0 5 150C X 195 hours 0 0 5 [Physical properties of the vulcanization produetl Tensile strength (Kg/cm I24 124 I23 I41 300 modulus (Kg/cm) 6I 75 72 I20 Elon ation (11) 820 700 700 450 Har ness (HS) 63 63 63 67 Tensile stre (Kg/ m) alter aged at I5 C. in a gear oven For 6 days. 73 For I4 days 56 I3 I5 Pennanent compression set 150C X 70 hours X compression 73.562.0 53.0 8|.4

' The test was conducted in'the same way as in Example 4. The results were evaluated on a scale of 0 to 5, in which 0 indicates no occurrence of con osion and 5 indicates the oecur'rene of corrosion all over the surface.

It is clear from Table 4 that the compositions of this invention have no corrosive attack on metal, and the vulcanization products thereof have excellent thermal stability and low permanent compression set. The results obtained by using the conventional vulcanization agent (Run No. 22) are inferior to those obtained by using the vulcanization agents of this invention.

EXAMPLE 6 The procedure of Example 5 was repeated except that the compounding recipe shown in Table 5 was used. The corrosive attack on metal of the resulting compositions and the vulcanization properties thereof were tested. The results are given in Table 5.

TABLE 5 Run No. 25 23 24 (Referential Example) [Compounding-ingredients,

by weight] pichIorohydr'in-ethylene oxide eopolymer rubber I00 I00 Tin stearate 2 2 FEF carbon black 40 40 40 2,2'-Methylene-bis-(4-methyI-6- tert.-butyl phenol) I I 1 Lead cyanate 3 3 Sorbitol 3 3 2-Mercaptoimidazoline I .5 Red lead 5 M ia 5 5 1 2- ercaptobenn'midazole 0.5

[Corrosive Attack on Metal") I50C. X 48 hours 0 0 0 I50C. X hours 0 0 3 C. X I68 hours 2 0 5 150C. X 2I6 hours 2 0 5 [Physical properties of the vulcanized'product] Tensile strengtlKKg/cm) I28 I26 I24 300 Modulus (Kg/cm) 93 86 I12 Elongation ($1) 560 600 360 Hardness (HS) 67 69 7I Pennanent compression set (11) I50C.X 70 hours 56.2 64.2 68.0

X 25 k compression Hydrin 00)(tradename, B. F. Goodrich o. Evaluated on a scale of 0 to 5 as mentioned before.

It is seen from Table 5 that the compositions of this invention have a lesser corrosive attack on metal than the composition containing the conventional vulcanization agent, and give vulcanization products having a low permanent compression set and an equal tensile strength as compared with the composition containing the conventional vulcanization agent.

What we claim is:

l. A vulcanizable epihalohydrin polymer elastomer comprising (1) an epihalhydrin polymer elastomer, (2) at least one metal cyanate selected from the group consisting of cyanates of metals of Groups IA, 18, IIA, [I8 and 'IVB of the periodic table, and (3) a functional compound selected from the group consisting of (i) compounds obtained by substituting at least two hydroxyl groups or mercapto groups for hydrogen atoms in a saturated hydrocarbon molecule, (ii) compounds obtained by substituting at least one hydroxyl group and at least one mercapto group for hydrogen atoms in a saturated hydrocarbon molecule, and (iii) compounds obtained by substituting at least one hydroxyl group or mercapto group or at least one hydroxyl group and mercapto group and one amino or imino group for hydrogen atoms in a saturated hydrocarbon molecule.

2. The composition of claim 1, wherein said epihalohydrin polymer elastomer is an epichlorohydrin homopolymer rubber or an epichlorohydrin-ethylene oxide copolymer rubber.

3. The composition of claim 1, wherein said metal cyanate is sodium cyanate, potassium cyanate, or lead cyanate.

4. The composition of claim 1, wherein said functional compound is a compound having 2 to 6 hydroxyl groups in the molecule.

5. A process for vulcanizing an epihalohydrin polymer elastomer, which comprises heating the epihalohydrin polymer elastomer at a temperature of about 120 to 180C. in the presence of at least one metal cyanate selected from the group consisting of cyanates of metals of Groups IA, 18, 11A, IIB and WE of the periodic table, and a functional compound selected from the group consisting of (i) compounds obtained by substituting at least two hydroxyl groups or mercapto groups for hydrogen atoms in a saturated hydrocarbon molecule, (ii) compounds obtained by substituting at least one hydroxyl group and at least one mercapto group for hydrogen atoms in a saturated hydrocarbon molecule, and (iii) compounds obtained by substituting at least one hydroxyl group or mercapto group or at least IIB and WE of the periodic table, (3) a functional com-' pound selected from the group consisting of (i) compounds obtained by substituting at least two hydroxyl groups or mercapto groups for hydrogen atoms in a saturated hydrocarbon molecule, (ii) compounds obtained by substituting at least one hydroxyl group and at least one mercapto group for hydrogen atoms in a saturated hydrocarbon molecule, and (iii) compounds obtained by substituting at least one hydroxyl group or mercapto group or at least one hydroxyl group and mercapto group and one amino or imino group for hydrogen atoms in a saturated hydrocarbon molecule, and (4) at least one metal oxide selected from the group consisting of the oxides of metal of Groups IIB and [VB of the periodic table.

7. The composition of claim 6, wherein said epihalohydrin polymer elastomer is an epichlorohydrin homopolymer rubber or an epichlorohydrin-ethylene oxide copolymer rubber.

8. The composition of claim 6, wherein said metal cyanate is sodium cyanate, potassium cyanate, or lead cyanate.

9. The composition of claim 6, wherein said functional compound is a compound having 2 to 6 hydroxyl groups in the molecule.

10. The composition of claim 6, wherein said metal oxide is magnesia or red lead.

11. A process for vulcanizing an epihalohydrin polymer elastomer, which comprises heating the epihalohydrin polymer elastomer at a temperature of about to C. in the presence of at least one metal cyanate selected from the group consisting of cyanates of metals of Groups IA, 18, HA, IIB and [VB of the periodic table, a functional compound selected from the group consisting of (i) compounds obtained by substituting at least two hydroxyl groups or mercapto groups for hydrogen atoms in a saturated hydrocarbon molecule, (ii) compounds obtained by substituting at least one hydroxyl group and at least one mercapto group for hydrogen atoms in a saturated hydrocarbon molecule, and (iii) compounds obtained by substituting at least one hydroxyl group or mercapto group or at least one hydroxyl group and mercapto group and one amino or imino group for hydrogen atoms in a saturated hydrocarbon molecule, and (4) at least one metal oxide selected from the group consisting of the oxides of metal of Groups IIB and [VB of the periodic table.

* l i i 1 UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent No. 3,755,207 Dated August 2 8, 1973 Inventofls) Tetsuo KARATSU is certified tht error appears in the 'above-identified patent that said Letters Patent are hereby corrected as shown below:

and

In the Heading!" in "Claims priority, application Japan,

10580/71, March 3, 1971- 7 Signed and sealed this 1st day of, January 197a,

(SEAL) Attest:

EDWARD M.FLETCHER,'JR. I 'I RENE TEGTMEYER Attesting Officer v 7 Acting Commissioner of Patents i O- 7 I .6 i FQ F \m I I U SCOMM-PC 603764 59 g ya. nuvzumann muymnp QffIC E ug-su 

2. The composition of claim 1, wherein said epihalohydrin polymer elastomer is an epichlorohydrin homopolymer rubber or an epichlorohydrin-ethylene oxide copolymer rubber.
 3. The composition of claim 1, wherein said metal cyanate is sodium cyanate, potassium cyanate, or lead cyanate.
 4. The composition of claim 1, wherein said functional compound is a compound having 2 to 6 hydroxyl groups in the molecule.
 5. A process for vulcanizing an epihalohydrin polymer elastomer, which comprises heating the epihalohydrin polymer elastomer at a temperature of about 120* to 180*C. in the presence of at least one metal cyanate selected from the group consisting of cyanates of metals of Groups IA, IB, IIA, IIB and IVB of the periodic table, and a functional compound selected from the group consisting of (i) compounds obtained by substituting at least two hydroxyl groups or mercapto groups for hydrogen atoms in a saturated hydrocarbon molecule, (ii) compounds obtained by substituting at least one hydroxyl group and at least one mercapto group for hydrogen atoms in a saturated hydrocarbon molecule, and (iii) compounds obtained by substituting at least one hydroxyl group or mercapto group or at least one hydroxyl group and mercapto group and one amino or imino group for hydrogen atoms in a saturated hydrocarbon molecule.
 6. A vulcanizable epihalohydrin polymer elastomer comprising (1) an epihalohydrin polymer elastomer, (2) at least one metal cyanate selected from the group consisting of cyanates of metals of Groups IA, IB, IIA, IIB and IVB of the periodic table, (3) a functional compound selected from the group consisting of (i) compounds obtained by substituting at least two hydroxyl groups or mercapto groups for hydrogen atoms in a saturated hydrocarbon molecule, (ii) compounds obtained by substituting at least one hydroxyl group and at least one mercapto group for hydrogen atoms in a saturated hydrocarbon molecule, and (iii) compounds obtained by substituting at least one hydroxyl group or mercapto group or at least one hydroxyl group and mercapto group and one amino or imino group for hydrogen atoms in a saturated hydrocarbon molecule, and (4) at least one metal oxide selected from the group consisting of the oxides of metal of Groups IIB and IVB of the periodic table.
 7. The composition of claim 6, wherein said epihalohydrin polymer elastomer is an epichlorohydrin homopolymer rubber or an epichlorohydrin-ethylene oxide copolymer rubber.
 8. The composition of claim 6, wherein said metal cyanate is sodium cyanate, potassium cyanate, or lead cyanate.
 9. The composition of claim 6, wherein said functional compound is a compound having 2 to 6 hydroxyl groups in the molecule.
 10. The composition of claim 6, wherein said metal oxide is magnesia or red lead.
 11. A process for vulcanizing an epihalohydrin polymer elastomer, which comprises heating the epihalohydrin polymer elastomer at a temperature of about 120* to 180*C. in the presence of at least one metal cyanate selected from the group consisting of cyanates of metals of Groups IA, IB, IIA, IIB and IVB of the periodic table, a functional compound selected from the group consisting of (i) compounds obtained by substituting at least two hydroxyl groups or mercapto groups for hydrogen atoms in a saturated hydrocarbon molecule, (ii) compounds obtained by substituting at least one hydroxyl group and at least one mercapto group for hydrogen atoms in a saturated hydrocarbon molecule, and (iii) compounds obtained by substituting at least one hydroxyl group or mercapto group or at least one hydroxyl group and mercapto group and one amino or imino group for hydrogen atoms in a saturated hydrocarbon molecule, and (4) at least one metal oxide selected from the group consisting of the oxides of metal of Groups IIB and IVB of the periodic table. 